Clase de laboratorio 01: propiedades físicas

Mecánica de Suelos y GeologíaFacultad de Ingeniería, Universidad de Buenos Aires

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pH and Salinity 73

Figure 6.3 Equipment used to measure the electrical con-ductivity of pore fl uid: electrical conductivity probe connected to a handheld meter.

Important considerations for the measurement of salinity include:

The centrifuge is used to accelerate the rate at which particles will fall out of suspension. The smaller clay particles have the most potential to stay in solution and are also the particles with the most surface charge. These small particles will function as ions and alter the measurement. The supernatant should be clear when making the measurements. Cleaning the probe is essential for reproducible results. A small drop of dis-tilled water or saline water from a prior measurement will immediately change the concentration of the small volume of the supernatant. The probe must be meticulously washed and dried in between each measurement. Purity of distilled water is important to the measurement since contamination in the water will increase the conductivity. The error is more important as the

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0.1 1 10 100 1,000Sea Salt Concentration, SS (g/L)

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Figure 6.4 Relationship between normalized electrical conductivity and sea salt con-centration.

Índice

• Ámbito de laboratorio• Ensayos

– Inspección tacto-visual– Gravedad específica– Humedad gravimétrica– Pesos unitarios– Densidad máxima y mínima– Análisis granulométrico – Hidrometría– Límites de Atterberg

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Ámbito de laboratorio

• ¿Qué es un laboratorio?• Es un ámbito de trabajo capacitado para la recepción,

análisis y almacenamiento de muestras de diferentenaturaleza, con sectores de trabajo delimitados.

• Debe asegurarse de que las condiciones ambientales no invaliden los resultados ni comprometan la calidadrequerida de las mediciones.

• Debe controlarse el acceso y el uso de las áreas que afectan a la calidad de los ensayos.

• Debe tener personal calificado.• Debe contar con procedimientos de trabajo.

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Ámbito de laboratorio

• Instalaciones mínimas• Podemos subdividir los sectores del laboratorio en:

– sectores secos– sectores húmedos– sectores con control higrotérmico– sectores sensibles a ruidos o vibraciones– sectores de almacenamiento– sectores de residuos– otros..

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Ámbito de laboratorio

• Equipamiento e instrumental• Acorde con el alcance del

laboratorio.• Deben ser utilizados por

personal calificado.• Verificar su correcto

funcionamiento o calibración antes de uso.

• Establecer período de calibración, en función del uso.

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SI NO12345

SI NO1234567

1DIARIA ANUAL EXTERNA NO

23456789

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1SI NO

23456789

101112131415161718

¿ Terceriza alguno de sus ensayos ?

¿ Las empresas a las cuales terceriza están acreditadas u aprobadas por algún organismo ?

2 - TRAZABILIDAD

1 - DISPOSICIÓN DE AMBIENTES DE TRABAJO

¿ Cuenta el laboratorio con ambientes con temperatura controlada ?¿ Cuenta el laboratorio con líneas de presión, vacío y agua ?

¿ Hay un procedimiento para el control de calidad de resultados ?¿ Se almacenan algunas muestras como registro del trabajo efectuado ?

3 - EQUIPAMIENTO PARA ENSAYOS DE RUTINA

Calibraciones¿ Entregó inventario de equipos e insumos ?

INSPECCIÓN TÉCNICA DE LABORATORIOSFecha de visitaEmpresa inspeccionada

EvaluadoresRepresentante empresa

Dirección

0 - INSTALACIONES DEL LABORATORIO

¿ Cuenta el laboratorio con matafuegos en los sectores de trabajo ?¿ Cuenta el laboratorio con adecuada iluminación ?¿ Cuenta el laboratorio con ambientes secos y húmedos separados ?

Se visitó el laboratorio en la fecha indicada, corroborando la existencia del establecimiento.

¿ Identifica el ingreso del material por escrito ?¿ Cuenta el laboratorio con espacio destinado a recepción de muestras ?¿ Se conservan registros de las planillas de campo ?¿ Las muestras a ensayar se ubican en sectores con Tº controlada ?

CBR

Calibraciones

FlexímetrosArosCascadorTamices

ManómetrosPesas

HornosBalanzas

Termómetros

¿ Se conservan los registros de los ensayos efectuados ?

Ensayos químicos (cloruros, sulfatos, sales, pH)Pin hole

Permeámetro carga variableCompresión simple rocasTriaxial rocasCompresión diametral rocas

Corte directoEdómetrosPermeámetro carga constante

4 - EQUIPAMIENTO PARA ENSAYOS ESPECÍFICOS¿ Entregó inventario de equipos e insumos ?

ClasificaciónHumedad naturalProctor

Presiones neutras

Gravedad específicaHidrometríaTriaxial

Firma del evaluador Firma representante empresa

5 - TRABAJOS A TERCEROS

Ensayos químicos y de contaminación

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Ensayos

• Los ensayos de caracterización física de un material son indispensables en cualquier proyecto de investigación, como así también los ensayos de caracterización hidráulica, mecánica, química, etc.

• A continuación se presentan los ensayos de laboratorio rutinarios para caracterización física de suelos con fines geotécnicos (existen otros).

• Conocer la metodología de ejecución de los ensayos nos permite conocer que cantidad de material necesito, como debe venir la muestra del campo al laboratorio, cuanto demora el trabajo en laboratorio y que dispersión de resultados se obtiene en la medición.

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Inspección tacto-visual

• Definición: descripción cualitativa de la muestra de suelo con propósitos ingenieriles.

• Ensayo: i) tomar una muestra de suelo, ii) observarla a la vista o con lupa o con microscopio, tocarla, sentir la textura, mojar con agua, tratar de romper un bloque, etc..

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Maximum Particle Size,Sieve Opening

Minimum Specimen Size,Dry Weight

4.75 mm (No. 4) 100 g (0.25 lb)9.5 mm (3⁄8 in.) 200 g (0.5 lb)19.0 mm (3⁄4 in.) 1.0 kg (2.2 lb)38.1 mm (11⁄2 in.) 8.0 kg (18 lb)75.0 mm (3 in.) 60.0 kg (132 lb)

NOTE 8—If random isolated particles are encountered that are signifi-cantly larger than the particles in the soil matrix, the soil matrix can beaccurately described and identified in accordance with the preceedingschedule.

9.4 If the field sample or specimen being examined issmaller than the minimum recommended amount, the reportshall include an appropriate remark.

10. Descriptive Information for Soils10.1 Angularity—Describe the angularity of the sand

(coarse sizes only), gravel, cobbles, and boulders, as angular,subangular, subrounded, or rounded in accordance with thecriteria in Table 1 and Fig. 3. A range of angularity may bestated, such as: subrounded to rounded.10.2 Shape—Describe the shape of the gravel, cobbles, and

boulders as flat, elongated, or flat and elongated if they meetthe criteria in Table 2 and Fig. 4. Otherwise, do not mention theshape. Indicate the fraction of the particles that have the shape,such as: one-third of the gravel particles are flat.10.3 Color—Describe the color. Color is an important

property in identifying organic soils, and within a givenlocality it may also be useful in identifying materials of similargeologic origin. If the sample contains layers or patches of

varying colors, this shall be noted and all representative colorsshall be described. The color shall be described for moistsamples. If the color represents a dry condition, this shall bestated in the report.10.4 Odor—Describe the odor if organic or unusual. Soils

containing a significant amount of organic material usuallyhave a distinctive odor of decaying vegetation. This is espe-cially apparent in fresh samples, but if the samples are dried,the odor may often be revived by heating a moistened sample.If the odor is unusual (petroleum product, chemical, and thelike), it shall be described.10.5 Moisture Condition—Describe the moisture condition

as dry, moist, or wet, in accordance with the criteria in Table 3.10.6 HCl Reaction—Describe the reaction with HCl as

none, weak, or strong, in accordance with the critera in Table4. Since calcium carbonate is a common cementing agent, areport of its presence on the basis of the reaction with dilutehydrochloric acid is important.10.7 Consistency—For intact fine-grained soil, describe the

NOTE 1—Percentages are based on estimating amounts of fines, sand, and gravel to the nearest 5 %.FIG. 2 Flow Chart for Identifying Coarse-Grained Soils (less than 50 % fines)

TABLE 1 Criteria for Describing Angularity of Coarse-GrainedParticles (see Fig. 3)

Description Criteria

Angular Particles have sharp edges and relatively plane sides withunpolished surfaces

Subangular Particles are similar to angular description but haverounded edges

Subrounded Particles have nearly plane sides but have well-roundedcorners and edges

Rounded Particles have smoothly curved sides and no edges

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14.9 If the soil is estimated to have 15 to 25 % sand orgravel, or both, the words “with sand” or “with gravel”(whichever is more predominant) shall be added to the groupname. For example: “lean clay with sand, CL” or “silt withgravel, ML” (see Fig. 1a and Fig. 1b). If the percentage of sandis equal to the percentage of gravel, use “with sand.”14.10 If the soil is estimated to have 30 % or more sand or

gravel, or both, the words “sandy” or “gravelly” shall be addedto the group name. Add the word “sandy” if there appears to bemore sand than gravel. Add the word “gravelly” if thereappears to be more gravel than sand. For example: “sandy leanclay, CL”, “gravelly fat clay, CH”, or “sandy silt, ML” (see Fig.1a and Fig. 1b). If the percentage of sand is equal to the percentof gravel, use “sandy.”

15. Procedure for Identifying Coarse-Grained Soils(Contains less than 50 % fines)

15.1 The soil is a gravel if the percentage of gravel isestimated to be more than the percentage of sand.15.2 The soil is a sand if the percentage of gravel is

estimated to be equal to or less than the percentage of sand.15.3 The soil is a clean gravel or clean sand if the

percentage of fines is estimated to be 5 % or less.15.3.1 Identify the soil as a well-graded gravel, GW, or as a

well-graded sand, SW, if it has a wide range of particle sizesand substantial amounts of the intermediate particle sizes.15.3.2 Identify the soil as a poorly graded gravel, GP, or as

a poorly graded sand, SP, if it consists predominantly of onesize (uniformly graded), or it has a wide range of sizes withsome intermediate sizes obviously missing (gap or skipgraded).15.4 The soil is either a gravel with fines or a sand with fines

if the percentage of fines is estimated to be 15 % or more.15.4.1 Identify the soil as a clayey gravel, GC, or a clayey

sand, SC, if the fines are clayey as determined by theprocedures in Section 14.15.4.2 Identify the soil as a silty gravel, GM, or a silty sand,

SM, if the fines are silty as determined by the procedures inSection 14.15.5 If the soil is estimated to contain 10 % fines, give the

soil a dual identification using two group symbols.15.5.1 The first group symbol shall correspond to a clean

gravel or sand (GW, GP, SW, SP) and the second symbol shallcorrespond to a gravel or sand with fines (GC, GM, SC, SM).15.5.2 The group name shall correspond to the first group

symbol plus the words “with clay” or “with silt” to indicate theplasticity characteristics of the fines. For example: “well-graded gravel with clay, GW-GC” or “poorly graded sand withsilt, SP-SM” (see Fig. 2).15.6 If the specimen is predominantly sand or gravel but

contains an estimated 15 % or more of the other coarse-grainedconstituent, the words “with gravel” or “with sand” shall beadded to the group name. For example: “poorly graded gravelwith sand, GP” or “clayey sand with gravel, SC” (see Fig. 2).15.7 If the field sample contains any cobbles or boulders, or

both, the words “with cobbles” or “with cobbles and boulders”shall be added to the group name. For example: “silty gravelwith cobbles, GM.”

16. Report16.1 The report shall include the information as to origin,

and the items indicated in Table 13.NOTE 14—Example: Clayey Gravel with Sand and Cobbles, GC—

About 50 % fine to coarse, subrounded to subangular gravel; about 30 %fine to coarse, subrounded sand; about 20 % fines with medium plasticity,high dry strength, no dilatancy, medium toughness; weak reaction withHCl; original field sample had about 5 % (by volume) subroundedcobbles, maximum dimension, 150 mm.In-Place Conditions—Firm, homogeneous, dry, brownGeologic Interpretation—Alluvial fan

TABLE 11 Criteria for Describing PlasticityDescription Criteria

Nonplastic A 1⁄8-in. (3-mm) thread cannot be rolled at any water contentLow The thread can barely be rolled and the lump cannot be

formed when drier than the plastic limitMedium The thread is easy to roll and not much time is required to

reach the plastic limit. The thread cannot be rerolled afterreaching the plastic limit. The lump crumbles when drierthan the plastic limit

High It takes considerable time rolling and kneading to reach theplastic limit. The thread can be rerolled several times afterreaching the plastic limit. The lump can be formed withoutcrumbling when drier than the plastic limit

TABLE 12 Identification of Inorganic Fine-Grained Soils fromManual Tests

SoilSymbol Dry Strength Dilatancy Toughness

ML None to low Slow to rapid Low or thread cannot beformed

CL Medium to high None to slow MediumMH Low to medium None to slow Low to mediumCH High to very high None High

TABLE 13 Checklist for Description of Soils1. Group name2. Group symbol3. Percent of cobbles or boulders, or both (by volume)4. Percent of gravel, sand, or fines, or all three (by dry weight)5. Particle-size range:

Gravel—fine, coarseSand—fine, medium, coarse

6. Particle angularity: angular, subangular, subrounded, rounded7. Particle shape: (if appropriate) flat, elongated, flat and elongated8. Maximum particle size or dimension9. Hardness of coarse sand and larger particles10. Plasticity of fines: nonplastic, low, medium, high11. Dry strength: none, low, medium, high, very high12. Dilatancy: none, slow, rapid13. Toughness: low, medium, high14. Color (in moist condition)15. Odor (mention only if organic or unusual)16. Moisture: dry, moist, wet17. Reaction with HCl: none, weak, strongFor intact samples:18. Consistency (fine-grained soils only): very soft, soft, firm, hard, very hard19. Structure: stratified, laminated, fissured, slickensided, lensed, homo-

geneous20. Cementation: weak, moderate, strong21. Local name22. Geologic interpretation23. Additional comments: presence of roots or root holes, presence of mica,

gypsum, etc., surface coatings on coarse-grained particles, caving orsloughing of auger hole or trench sides, difficulty in augering or excavating,etc.

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ASTM D2488

particles are hit by a hammer, for example, gravel-size particlesfracture with considerable hammer blow, some gravel-sizeparticles crumble with hammer blow. “Hard” means particlesdo not crack, fracture, or crumble under a hammer blow.10.13 Additional comments shall be noted, such as the

presence of roots or root holes, difficulty in drilling or augeringhole, caving of trench or hole, or the presence of mica.10.14 A local or commercial name or a geologic interpre-

tation of the soil, or both, may be added if identified as such.10.15 A classification or identification of the soil in accor-

dance with other classification systems may be added ifidentified as such.

11. Identification of Peat11.1 A sample composed primarily of vegetable tissue in

various stages of decomposition that has a fibrous to amor-

phous texture, usually a dark brown to black color, and anorganic odor, shall be designated as a highly organic soil andshall be identified as peat, PT, and not subjected to theidentification procedures described hereafter.

12. Preparation for Identification12.1 The soil identification portion of this practice is based

on the portion of the soil sample that will pass a 3-in. (75-mm)sieve. The larger than 3-in. (75-mm) particles must be re-moved, manually, for a loose sample, or mentally, for an intactsample before classifying the soil.12.2 Estimate and note the percentage of cobbles and the

percentage of boulders. Performed visually, these estimateswill be on the basis of volume percentage.NOTE 9—Since the percentages of the particle-size distribution in Test

Method D 2487 are by dry weight, and the estimates of percentages forgravel, sand, and fines in this practice are by dry weight, it is recom-mended that the report state that the percentages of cobbles and bouldersare by volume.

12.3 Of the fraction of the soil smaller than 3 in. (75 mm),estimate and note the percentage, by dry weight, of the gravel,sand, and fines (see Appendix X4 for suggested procedures).NOTE 10—Since the particle-size components appear visually on the

basis of volume, considerable experience is required to estimate thepercentages on the basis of dry weight. Frequent comparisons withlaboratory particle-size analyses should be made.

12.3.1 The percentages shall be estimated to the closest 5 %.The percentages of gravel, sand, and fines must add up to100 %.12.3.2 If one of the components is present but not in

sufficient quantity to be considered 5 % of the smaller than3-in. (75-mm) portion, indicate its presence by the term trace,for example, trace of fines. A trace is not to be considered in thetotal of 100 % for the components.

13. Preliminary Identification13.1 The soil is fine grained if it contains 50 % or more

fines. Follow the procedures for identifying fine-grained soilsof Section 14.13.2 The soil is coarse grained if it contains less than 50 %

fines. Follow the procedures for identifying coarse-grainedsoils of Section 15.

14. Procedure for Identifying Fine-Grained Soils14.1 Select a representative sample of the material for

examination. Remove particles larger than the No. 40 sieve(medium sand and larger) until a specimen equivalent to abouta handful of material is available. Use this specimen forperforming the dry strength, dilatancy, and toughness tests.14.2 Dry Strength:14.2.1 From the specimen, select enough material to mold

into a ball about 1 in. (25 mm) in diameter. Mold the materialuntil it has the consistency of putty, adding water if necessary.14.2.2 From the molded material, make at least three test

specimens. A test specimen shall be a ball of material about 1⁄2in. (12 mm) in diameter. Allow the test specimens to dry in air,or sun, or by artificial means, as long as the temperature doesnot exceed 60°C.

TABLE 3 Criteria for Describing Moisture ConditionDescription Criteria

Dry Absence of moisture, dusty, dry to the touchMoist Damp but no visible waterWet Visible free water, usually soil is below water table

TABLE 4 Criteria for Describing the Reaction With HClDescription Criteria

None No visible reactionWeak Some reaction, with bubbles forming slowlyStrong Violent reaction, with bubbles forming immediately

TABLE 5 Criteria for Describing ConsistencyDescription Criteria

Very soft Thumb will penetrate soil more than 1 in. (25 mm)Soft Thumb will penetrate soil about 1 in. (25 mm)Firm Thumb will indent soil about 1⁄4in. (6 mm)Hard Thumb will not indent soil but readily indented with thumbnailVery hard Thumbnail will not indent soil

TABLE 6 Criteria for Describing CementationDescription Criteria

Weak Crumbles or breaks with handling or little finger pressureModerate Crumbles or breaks with considerable finger pressureStrong Will not crumble or break with finger pressure

TABLE 7 Criteria for Describing StructureDescription Criteria

Stratified Alternating layers of varying material or color with layers atleast 6 mm thick; note thickness

Laminated Alternating layers of varying material or color with thelayers less than 6 mm thick; note thickness

Fissured Breaks along definite planes of fracture with littleresistance to fracturing

Slickensided Fracture planes appear polished or glossy, sometimesstriated

Blocky Cohesive soil that can be broken down into small angularlumps which resist further breakdown

Lensed Inclusion of small pockets of different soils, such as smalllenses of sand scattered through a mass of clay; notethickness

Homogeneous Same color and appearance throughout

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particles are hit by a hammer, for example, gravel-size particlesfracture with considerable hammer blow, some gravel-sizeparticles crumble with hammer blow. “Hard” means particlesdo not crack, fracture, or crumble under a hammer blow.10.13 Additional comments shall be noted, such as the

presence of roots or root holes, difficulty in drilling or augeringhole, caving of trench or hole, or the presence of mica.10.14 A local or commercial name or a geologic interpre-

tation of the soil, or both, may be added if identified as such.10.15 A classification or identification of the soil in accor-

dance with other classification systems may be added ifidentified as such.

11. Identification of Peat11.1 A sample composed primarily of vegetable tissue in

various stages of decomposition that has a fibrous to amor-

phous texture, usually a dark brown to black color, and anorganic odor, shall be designated as a highly organic soil andshall be identified as peat, PT, and not subjected to theidentification procedures described hereafter.

12. Preparation for Identification12.1 The soil identification portion of this practice is based

on the portion of the soil sample that will pass a 3-in. (75-mm)sieve. The larger than 3-in. (75-mm) particles must be re-moved, manually, for a loose sample, or mentally, for an intactsample before classifying the soil.12.2 Estimate and note the percentage of cobbles and the

percentage of boulders. Performed visually, these estimateswill be on the basis of volume percentage.NOTE 9—Since the percentages of the particle-size distribution in Test

Method D 2487 are by dry weight, and the estimates of percentages forgravel, sand, and fines in this practice are by dry weight, it is recom-mended that the report state that the percentages of cobbles and bouldersare by volume.

12.3 Of the fraction of the soil smaller than 3 in. (75 mm),estimate and note the percentage, by dry weight, of the gravel,sand, and fines (see Appendix X4 for suggested procedures).NOTE 10—Since the particle-size components appear visually on the

basis of volume, considerable experience is required to estimate thepercentages on the basis of dry weight. Frequent comparisons withlaboratory particle-size analyses should be made.

12.3.1 The percentages shall be estimated to the closest 5 %.The percentages of gravel, sand, and fines must add up to100 %.12.3.2 If one of the components is present but not in

sufficient quantity to be considered 5 % of the smaller than3-in. (75-mm) portion, indicate its presence by the term trace,for example, trace of fines. A trace is not to be considered in thetotal of 100 % for the components.

13. Preliminary Identification13.1 The soil is fine grained if it contains 50 % or more

fines. Follow the procedures for identifying fine-grained soilsof Section 14.13.2 The soil is coarse grained if it contains less than 50 %

fines. Follow the procedures for identifying coarse-grainedsoils of Section 15.

14. Procedure for Identifying Fine-Grained Soils14.1 Select a representative sample of the material for

examination. Remove particles larger than the No. 40 sieve(medium sand and larger) until a specimen equivalent to abouta handful of material is available. Use this specimen forperforming the dry strength, dilatancy, and toughness tests.14.2 Dry Strength:14.2.1 From the specimen, select enough material to mold

into a ball about 1 in. (25 mm) in diameter. Mold the materialuntil it has the consistency of putty, adding water if necessary.14.2.2 From the molded material, make at least three test

specimens. A test specimen shall be a ball of material about 1⁄2in. (12 mm) in diameter. Allow the test specimens to dry in air,or sun, or by artificial means, as long as the temperature doesnot exceed 60°C.

TABLE 3 Criteria for Describing Moisture ConditionDescription Criteria

Dry Absence of moisture, dusty, dry to the touchMoist Damp but no visible waterWet Visible free water, usually soil is below water table

TABLE 4 Criteria for Describing the Reaction With HClDescription Criteria

None No visible reactionWeak Some reaction, with bubbles forming slowlyStrong Violent reaction, with bubbles forming immediately

TABLE 5 Criteria for Describing ConsistencyDescription Criteria

Very soft Thumb will penetrate soil more than 1 in. (25 mm)Soft Thumb will penetrate soil about 1 in. (25 mm)Firm Thumb will indent soil about 1⁄4in. (6 mm)Hard Thumb will not indent soil but readily indented with thumbnailVery hard Thumbnail will not indent soil

TABLE 6 Criteria for Describing CementationDescription Criteria

Weak Crumbles or breaks with handling or little finger pressureModerate Crumbles or breaks with considerable finger pressureStrong Will not crumble or break with finger pressure

TABLE 7 Criteria for Describing StructureDescription Criteria

Stratified Alternating layers of varying material or color with layers atleast 6 mm thick; note thickness

Laminated Alternating layers of varying material or color with thelayers less than 6 mm thick; note thickness

Fissured Breaks along definite planes of fracture with littleresistance to fracturing

Slickensided Fracture planes appear polished or glossy, sometimesstriated

Blocky Cohesive soil that can be broken down into small angularlumps which resist further breakdown

Lensed Inclusion of small pockets of different soils, such as smalllenses of sand scattered through a mass of clay; notethickness

Homogeneous Same color and appearance throughout

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Inspección tacto-visual

• Ejemplo 1: Gravas angulares con presencia de arenas y finos no plásticos, con presencia de mineral de yeso.

• Ejemplo 2: Arcilla plástica uniforme, blanda, con presencia de restos de conchillas marinas en forma errática.

• Ejemplo 3: Limo no plástico, parcialmente cementado.

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EJ. 1 EJ. 2 EJ. 3

Gravedad específica

• Definición: relación entre el peso específico de las partículas sólidas (!!) y el peso específico del agua (!").

• Expresión: "! =#!#"= $$!/&!

#"

• Ensayo: "!# =$!

$$,"'$! ($$,",&!• Se corrige por temperatura "! =")#

#"##"'(°

• Tamaño de muestra 30 – 100gr.

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*+,-,*!

Balanza +/- 0.01gr

Gravedad específica

• Valores típicos "! (rango de variación pequeño), requiere mucha precisión el ensayo.

• Es una propiedad intrínseca del material, no cambia.• Se limita el ensayo a suelo pasante #4 (otra técnica para

suelos gruesos)

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Humedad gravimétrica

• Definición: relación entre el peso de agua (%.) y el peso seco de las partículas sólidas (%!).

• Expresión: & = $"$!

• Ensayo:& = $#*+*" ($#*+$#*+ ($#

• Secado en horno 110 +/- 5ºC.• El tiempo de secado puede variar

según tipo de muestra (arenas limpias 4hs, suelos finos >16hr).

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/ (1232)

Horno de secado y recipientes (pesafiltros)

Humedad gravimétrica

• NO HAY valores típicos de &, amplio rango de variación.

• La precisión buscada y tipo dematerial definen la cantidad de suelo a ensayar (grs o kilos).

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D 6026 Guide for Using Significant Digits in Calculatingand Reporting Geotechnical Test Data5E 145 Specification for Gravity-Convection And Forced-Ventilation Ovens6

3. Terminology3.1 Refer to Terminology D 653 for standard definitions of

terms.3.2 Definitions of Terms Specific to This Standard:3.2.1 water content (of a material)—the ratio expressed as a

percent of the mass of “pore” or “free” water in a given massof material to the mass of the solid material. A standardtemperature of 110° 6 5°C is used to determine these masses.

4. Summary of Test Method4.1 A test specimen is dried in an oven at a temperature of

110° 6 5°C to a constant mass. The loss of mass due to dryingis considered to be water. The water content is calculated usingthe mass of water and the mass of the dry specimen.

5. Significance and Use5.1 For many materials, the water content is one of the most

significant index properties used in establishing a correlationbetween soil behavior and its index properties.5.2 The water content of a material is used in expressing the

phase relationships of air, water, and solids in a given volumeof material.5.3 In fine-grained (cohesive) soils, the consistency of a

given soil type depends on its water content. The water contentof a soil, along with its liquid and plastic limits as determinedby Test Method D 4318, is used to express its relative consis-tency or liquidity index.

6. Apparatus6.1 Drying Oven, thermostatically-controlled, preferably of

the forced-draft type, meeting the requirements of Specifica-tion E 145 and capable of maintaining a uniform temperatureof 110 6 5°C throughout the drying chamber.6.2 Balances—All balances must meet the requirements of

Specification D 4753 and this section. A Class GP1 balance of0.01g readability is required for specimens having a mass of upto 200 g (excluding mass of specimen container) and a ClassGP2 balance of 0.1g readability is required for specimenshaving a mass over 200 g. However, the balance used may becontrolled by the number of significant digits needed (see 8.2.1and 12.1.2).6.3 Specimen Containers—Suitable containers made of ma-

terial resistant to corrosion and change in mass upon repeatedheating, cooling, exposure to materials of varying pH, andcleaning. Unless a dessicator is used, containers with close-fitting lids shall be used for testing specimens having a mass ofless than about 200 g; while for specimens having a massgreater than about 200 g, containers without lids may be used(see Note 7). One container is needed for each water contentdetermination.

NOTE 2—The purpose of close-fitting lids is to prevent loss of moisturefrom specimens before initial mass determination and to prevent absorp-tion of moisture from the atmosphere following drying and before finalmass determination.

6.4 Desiccator—A desiccator cabinet or large desiccator jarof suitable size containing silica gel or anhydrous calciumsulfate. It is preferable to use a desiccant which changes colorto indicate it needs reconstitution. See 10.5.NOTE 3—Anhydrous calcium sulfate is sold under the trade name

Drierite.

6.5 Container Handling Apparatus, gloves, tongs, or suit-able holder for moving and handling hot containers afterdrying.6.6 Miscellaneous, knives, spatulas, scoops, quartering

cloth, sample splitters, etc, as required.

7. Samples7.1 Samples shall be preserved and transported in accor-

dance with Practice 4220 Groups B, C, or D soils. Keep thesamples that are stored prior to testing in noncorrodible airtightcontainers at a temperature between approximately 3 and 30°Cand in an area that prevents direct contact with sunlight.Disturbed samples in jars or other containers shall be stored insuch a way as to prevent or minimize moisture condensation onthe insides of the containers.7.2 The water content determination should be done as soon

as practicable after sampling, especially if potentially corrod-ible containers (such as thin-walled steel tubes, paint cans, etc.)or plastic sample bags are used.

8. Test Specimen8.1 For water contents being determined in conjunction with

another ASTM method, the specimen mass requirement statedin that method shall be used if one is provided. If no minimumspecimen mass is provided in that method then the values givenbelow shall apply. See Howard7 for background data for thevalues listed.8.2 The minimum mass of moist material selected to be

representative of the total sample shall be in accordance withthe following:

Maximum particlesize (100 %passing)

Standard SieveSize

Recommendedminimum mass ofmoist test spec-imen for watercontent reported

to 60.1 %

Recommendedminimum mass ofmoist test spec-imen for watercontent reported

to 61 %

2 mm or less No. 10 20 g 20 gA4.75 mm No. 4 100 g 20 gA9.5 mm 3⁄8-in. 500 g 50 g19.0 mm 3⁄4-in. 2.5 kg 250 g37.5 mm 11⁄2 in. 10 kg 1 kg75.0 mm 3-in. 50 kg 5 kg

ATo be representative not less than 20 g shall be used.8.2.1 The minimum mass used may have to be increased to

obtain the needed significant digits for the mass of water whenreporting water contents to the nearest 0.1 % or as indicated in12.1.2.

5 Annual Book of ASTM Standards, Vol 04.09.6 Annual Book of ASTM Standards, Vol 14.02.

7 Howard, A. K., “Minimum Test Specimen Mass for Moisture Content Deter-mination”, Geotechnical Testing Journal,A.S.T.M., Vol. 12, No. 1, March 1989, pp.39-44.

D 2216

2

grueso + finos

finos(ASTM D2216 – moisture content)

Humedad gravimétrica

• Si seco a mayor temperatura, sale más agua pero no estoy midiendo & bajo norma.

• Agua adsorbida (>400ºC), agua intermedia (150-200ºC) y agua poral (110ºC).

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the tetrahedral layer and is thus tightly bonded. Thesecharacteristics effectively preclude the admission ofsignificant amounts of water between the unit layers.

Clay mineral-water interaction 21-23,27

29. The electrical charges exhibited by clay.mineral grains

are caused by the following: (a) charge d fe iciencies due to ionic

substitution within the lattice, (b) broken bonds at grain edges,

(c) imperfections within the lattice, and (d) the polar nature of ions

exposed at clay surfaces. This last cause includes the negative elec-trical charge of oxygen in the silicon tetrahedral layer and a positive

charge due to the hydroxyl portion in the aluminum octahedral layer.

Lattice imperfections and broken bonds may produce either a positive

or negative charge, whereas ionic substitution usually results in a

negative charge.

30. The magnitude and location of these electrical charges are

different for the various clay minerals and are fundamental in ex-

plaining the ability of some minerals to imbibe significantly more

water than others. Water associated with the clay minerals consists

of three types:

a. Hydroxyl or bound water.- This water forms a part ofthe octahedral layer and cannot be removed by heatingat temperatures below 400° C for most clay minerals.

b* Interlayer water. This is double-layer water whichoccurs between clay mineral surfaces in some clays.It is gradually removed by heating up to l5O-2OO'C.

C . Pore water.- This water occurs in the open spacesbetween grains and also constitutes the more tightlybound double-layer water on grain surfaces. Thiswater is essentially removed by drying at room temper-atures and completely removed by heating atapproximately 100° C.

31. The clay minerals which exhibit appreciable expansion or

shrinkage are called expansive clay minerals and include montmoril-lonite, vermiculite, chlorite, and mixed-layer combinations of theseminerals with each other or with other clay minerals. Halloysite, thetubular, hydrous member of the kaolinite group may also exhibit expan-

sive properties. Kaolinite and illite generally do not exhibit volume

31

(FHWA. Expansive soils in highway subgrades)

Esto define la humedad

natural

13

Peso unitario húmedo

• Definición: relación entre el peso húmedo de la muestra de suelo (%5) y su volumen total ('5).

• Expresión: ! = $#&#

• Ensayo: ! = $#*+*" ($#&#

• %5')'. ,%5 → horno y balanza• '5 → calibre• Si la muestra viene alterada o

disturbada, no puedo medir !.• NO es una propiedad intrínseca del

material, cambia.

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14

Muestra de arcilla plástica (CH) del Postpampeano extraída con sacatestigo de reducida alteración

Peso unitario húmedo

• Amplio rango de variación.• NO es una propiedad

intrínseca del material.• !!67 > ! , siempre• Valores típicos (Zárate-

Campana, margen derecha Río Paraná):

– !89_;<!=6>= = 15 − 17 ?@>,

– !AB_;6>= = 18 − 20 ?@>,

– !);_;CDEFGD = 20 − 22 ?@>,

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15

EPRI Manual (Hough 1969)

Peso unitario seco

• Definición: relación entre el peso seco de la muestra de suelo (%)) y su volumen total ('5).

• Expresión: !H =$+&#

• Ensayo: !H =$#*+ ($#

&#• %5') ,%5 → horno y balanza• '5 → calibre

• Si previamente medí ! y 4 → !H =#

I'"(es la práctica

habitual en una rutina de laboratorio)• NO es una propiedad intrínseca del material, cambia.• !!67 > ! > !H , siempre

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16

Densidad relativa

• Definición: estado de densidad actual (5J) de un suelo relativo a su estado mas suelto (5>áL) y mas denso (5>íN).

• Expresión: 6O =D-á/ ( D(D-á/ ( D-í1

• Ensayo: se requieren 3 determinaciones

• 5J =&2&+= #!

#3− 1 → relación de vacíos actual

• 5>áL =#!

#3-í1− 1 → relación de vacíos máxima

• 5>íN =#!

#3-á/− 1 → relación de vacíos mínima

• NO es una propiedad intrínseca del material, cambia.• Mas representativo para caracterizar suelos gruesos.

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17

Densidad relativa

• 5J →medición en campo• 5>áL , 5>íN → medición en lab

• !H-á/ =$+

&#-í1→ mesa vibratoria

• !H-í1 =$+

&#-á/→ vertido controlado

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18

Determinación P>íN (mesa vibratoria)

Determinación P>áL (vertido controlado)EPRI Manual (Terzaghi & Peck, Lambe & Whitman)

Densidad relativa

• Depende del tamaño y forma de los granos• Difícil densificar suelos en campo a 6O > 85%

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19Maximum Density, Minimum Density 55

S oil T ype e max ρ min (g/cm 3 ) e min ρ max (g/cm 3 )

Processed Manchester Fine Sand *

0.909 1.408 0.580 1.701

2010 Industrial Quartz * * 0.955 1.355 0.640 1.616

Ticino Sand * * * 0.930 1.380 0.570 1.700

* After Andersen, 1991 ; values determined using D4253 and D4254.

* * After Sinfi eld, 1997 ; e min / ρ max determined using vibrating table and surcharge, methods for determining e max / ! min unknown.

* * * As appearing in Larson, 1992 (from Franco, 1989 ); methods unknown.

Figure 4.2 Equipment setup used for the pepper shaker method to determine maximum index density.

Other methods are also available, such as a wet tamping method (Head, 1980 ) for sands. This method is an approach that locks the particles in place using shearing action as the submerged surface is tamped with a mass attached to a vibrating hammer.

Many educational laboratories do not have vibrating tables at their disposal. There-fore, even though D4253 is the ASTM test method used to measure the maximum index density, in this text the concepts of preparing a dense specimen are provided using the pepper shaker method. While the pepper shaker method may not provide the same values of maximum density as the ASTM method, the results will generally be compa-rable. An example equipment setup using this method is presented in Figure 4.2 .

Typical values of the maximum void ratio, minimum void ratio, maximum mass density, and minimum mass density of selected soils are presented in Table 4.1 .

The volume of the mold can be determined either through direct measurement of the dimensions of the mold, or through the water fi lling method. The water fi lling method is presented below.

1. Measure the mass of the water tight mold (M m ) to 1 gram (or four signifi cant digits).

2. Fill the mold with equilibrated, distilled water to the calibration level. Measure the mass of the mold and water (M wm ) to 1 gram.

3. Calculate the mass of water (M w ) to 1 gram using Equation 4.3 :

T Y P I C A L VA L U E S

Table 4.1 Typical values of maximum void ratio, minimum void ratio, maximum mass den-sity, and minimum mass density of selected soils.

C A L I B R AT I O N

(Germaine J. 2009) (Q! = 2.68 WX/YZ[)

Análisis granulométrico

• Definición: Distribución de tamaño partículas en la muestra de suelo.

• Necesario para conocer USCS.• Ensayo: i) conocer %! de la muestra

ensayada, ii) aplicar solución de dispersante y reposo 24hs, iii) efectuar tamizado.

• Cantidad mínima de tamices: 6 a 8

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20 (ASTM D422 – sieve analysis – serie de tamices)

Agitador mecánico

3”

#4

#200marked for a volume of 1000 mL. The inside diameter shall besuch that the 1000-mL mark is 36 6 2 cm from the bottom onthe inside.3.5 Thermometer—A thermometer accurate to 1°F (0.5°C).3.6 Sieves—A series of sieves, of square-mesh woven-wire

cloth, conforming to the requirements of Specification E 11. Afull set of sieves includes the following (Note 6):

3-in. (75-mm) No. 10 (2.00-mm)2-in. (50-mm) No. 20 (850-µm)11⁄2-in. (37.5-mm) No. 40 (425-µm)1-in. (25.0-mm) No. 60 (250-µm)3⁄4-in. (19.0-mm) No. 140 (106-µm)3⁄8-in. (9.5-mm) No. 200 (75-µm)No. 4 (4.75-mm)

NOTE 6—A set of sieves giving uniform spacing of points for the graph,as required in Section 17, may be used if desired. This set consists of thefollowing sieves:

3-in. (75-mm) No. 16 (1.18-mm)11⁄2-in. (37.5-mm) No. 30 (600-µm)3⁄4-in. (19.0-mm) No. 50 (300-µm)3⁄8-in. (9.5-mm) No. 100 (150-µm)No. 4 (4.75-mm) No. 200 (75-µm)No. 8 (2.36-mm)

3.7 Water Bath or Constant-Temperature Room—A waterbath or constant-temperature room for maintaining the soilsuspension at a constant temperature during the hydrometeranalysis. A satisfactory water tank is an insulated tank thatmaintains the temperature of the suspension at a convenientconstant temperature at or near 68°F (20°C). Such a device isillustrated in Fig. 4. In cases where the work is performed in aroom at an automatically controlled constant temperature, thewater bath is not necessary.3.8 Beaker—A beaker of 250-mL capacity.3.9 Timing Device—A watch or clock with a second hand.

4. Dispersing Agent4.1 A solution of sodium hexametaphosphate (sometimes

called sodium metaphosphate) shall be used in distilled ordemineralized water, at the rate of 40 g of sodiumhexametaphosphate/litre of solution (Note 7).NOTE 7—Solutions of this salt, if acidic, slowly revert or hydrolyze

back to the orthophosphate form with a resultant decrease in dispersiveaction. Solutions should be prepared frequently (at least once a month) oradjusted to pH of 8 or 9 by means of sodium carbonate. Bottles containingsolutions should have the date of preparation marked on them.

4.2 All water used shall be either distilled or demineralizedwater. The water for a hydrometer test shall be brought to thetemperature that is expected to prevail during the hydrometertest. For example, if the sedimentation cylinder is to be placedin the water bath, the distilled or demineralized water to beused shall be brought to the temperature of the controlled waterbath; or, if the sedimentation cylinder is used in a room withcontrolled temperature, the water for the test shall be at thetemperature of the room. The basic temperature for the

Metric Equivalents

in. 0.001 0.049 0.203 1⁄2 3⁄4mm 0.03 1.24 5.16 12.7 19.0

FIG. 1 Detail of Stirring Paddles

Metric Equivalents

in. 1.3 2.6 3.75mm 33 66 95.2

FIG. 2 Dispersion Cups of Apparatus

D 422 – 63 (2002)

2

Dispersante (hexametafosfato de sodio)

Análisis granulométrico

• La cantidad de muestra a ensayar depende del tamaño máximo de partícula.

• Permite graduar tamaños de hasta 7589 = 0.07599• Graduación de tamaños > 7589 → hidrometría

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21

Muestra A

Muestra B

Identificar curva p/

muestra A y B

Análisis granulométricoLa

b 01

-pr

opie

dade

s fís

icas

22

2º) Planilla típica de laboratorio (posterior al secado a horno)

AOSA SA - Tacuarí 1184 C1071AAX - CABA - Tel: 4361 3869

www.aosa.com.ar - info@aosa.com.ar

Fecha : 2- DETERMINACIÓN RETENIDO TAMICESResponsable: R. Candela - A. EscobarObra: 5246 - K Piesold bandeja tara tara + PS

175 32,44 139,6413 8,65 211,38

nro (mm) (gr) (gr) (gr) (%) 16 17,14 4123" 75,00 0 0 3244 100 21 8,65 6932" 50,00 0 0 3244 100 20 8,75 480

1 1/2" 37,50 0 0 3244 100 23 8,83 180,171" 25,00 107 107 3137 97 22 8,59 148,18

3/4" 19,00 203 310 2934 90 19 8,67 4791/2" 12,50 395 705 2539 78 1 8,43 2363/8" 9,50 684 1389 1855 57 2 8,51 91,66N°4 4,75 471 1860 1384 43 3 8,66 47,17

N°10 2,00 171 2032 1212 37N°20 0,85 140 2171 1073 33N°40 0,42 470 2642 602 19N°60 0,25 228 2869 375 12

N°100 0,15 83 2952 292 9N°200 0,074 39 2991 253 8

D60 D30 D10 Cu Cc9,90 0,76 0,19 52,3 0,3 1- DETERMINACIÓN PESO SECO

Tamaño de muestra: 3244 gr tara bandejaPreparac: Pasada por mortero tara + bandeja húmeda

Agente dispersante durante 24 hs tara + bandeja secaGravas (G) : 57,3% LL 13 humedadArenas (S) : 34,8% LP S/D peso seco muestraFinos (C+M): 7,8%

CLASIFICACIÓN USCS GP-GM

ANÁLISIS GRANULOMÉTRICO20/812

Procedimiento de trabajo s/ ASTM D422-63R02

CRIBAS & TAMICES RET. PASANTERET. AC.

3" 2"1

1/2

" 1" 3/4

" 3/8

" Nº4

Nº 1

0

Nº 4

0

Nº 6

0

Nº 1

00

Nº20

0

''1/2 N°20

0

10

20

30

40

50

60

70

80

90

100

0,010,101,0010,00100,00

% P

asa

Tamaño teórico de partícula (mm)

MUESTRA TP-A-KP-03 H2

!

1º) Retenido por cada tamiz (previo secado a horno)

AOSA SA - Tacuarí 1184 C1071AAX - CABA - Tel: 4361 3869

www.aosa.com.ar - info@aosa.com.ar

Fecha : 2- DETERMINACIÓN RETENIDO TAMICESResponsable: R. Candela - A. EscobarObra: 5246 - K Piesold bandeja tara tara + PS

175 32,44 139,6413 8,65 211,38

nro (mm) (gr) (gr) (%) 16 17,14 4123" 75,00 0 3244 100 21 8,65 6932" 50,00 0 3244 100 20 8,75 480

1 1/2" 37,50 0 3244 100 23 8,83 180,171" 25,00 107 3137 97 22 8,59 148,18

3/4" 19,00 203 2934 90 19 8,67 4791/2" 12,50 395 2539 78 1 8,43 2363/8" 9,50 684 1855 57 2 8,51 91,66N°4 4,75 471 1384 43 3 8,66 47,17

N°10 2,00 171 1212 37N°20 0,85 140 1073 33N°40 0,42 470 602 19N°60 0,25 228 375 12

N°100 0,15 83 292 9N°200 0,074 39 253 8

D60 D30 D10 Cu Cc9,90 0,76 0,19 52,3 0,3 1- DETERMINACIÓN PESO SECO

Tamaño de muestra: 3244 gr tara bandejaPreparac: Pasada por mortero tara + bandeja húmeda

Agente dispersante durante 24 hs tara + bandeja secaGravas (G) : 57,3% LL 13 humedadArenas (S) : 34,8% LP S/D peso seco muestraFinos (C+M): 7,8%

CLASIFICACIÓN USCS GP-GM

ANÁLISIS GRANULOMÉTRICO20/812

Procedimiento de trabajo s/ ASTM D422-63R02

CRIBAS & TAMICES RET. PASANTE

3" 2"1

1/2

" 1" 3/4

" 3/8

" Nº4

Nº 1

0

Nº 4

0

Nº 6

0

Nº 1

00

Nº20

0

''1/2 N°20

0

10

20

30

40

50

60

70

80

90

100

0,010,101,0010,00100,00

% P

asa

Tamaño teórico de partícula (mm)

MUESTRA TP-A-KP-03 H2

!

AOSA SA - Tacuarí 1184 C1071AAX - CABA - Tel: 4361 3869

www.aosa.com.ar - info@aosa.com.ar

Fecha : 2- DETERMINACIÓN RETENIDO TAMICESResponsable: R. Candela - A. EscobarObra: 5246 - K Piesold bandeja tara tara + PS

175 32,44 139,6413 8,65 211,38

nro (mm) (gr) (gr) (%) 16 17,14 4123" 75,00 0 3244 100 21 8,65 6932" 50,00 0 3244 100 20 8,75 480

1 1/2" 37,50 0 3244 100 23 8,83 180,171" 25,00 107 3137 97 22 8,59 148,18

3/4" 19,00 203 2934 90 19 8,67 4791/2" 12,50 395 2539 78 1 8,43 2363/8" 9,50 684 1855 57 2 8,51 91,66N°4 4,75 471 1384 43 3 8,66 47,17

N°10 2,00 171 1212 37N°20 0,85 140 1073 33N°40 0,42 470 602 19N°60 0,25 228 375 12

N°100 0,15 83 292 9N°200 0,074 39 253 8

D60 D30 D10 Cu Cc9,90 0,76 0,19 52,3 0,3 1- DETERMINACIÓN PESO SECO

Tamaño de muestra: 3244 gr tara bandejaPreparac: Pasada por mortero tara + bandeja húmeda

Agente dispersante durante 24 hs tara + bandeja secaGravas (G) : 57,3% LL 13 humedadArenas (S) : 34,8% LP S/D peso seco muestraFinos (C+M): 7,8%

CLASIFICACIÓN USCS GP-GM

ANÁLISIS GRANULOMÉTRICO20/812

Procedimiento de trabajo s/ ASTM D422-63R02

CRIBAS & TAMICES RET. PASANTE

3" 2"1

1/2

" 1" 3/4

" 3/8

" Nº4

Nº 1

0

Nº 4

0

Nº 6

0

Nº 1

00

Nº20

0

''1/2 N°20

0

10

20

30

40

50

60

70

80

90

100

0,010,101,0010,00100,00

% P

asa

Tamaño teórico de partícula (mm)

MUESTRA TP-A-KP-03 H2

!

3º) Confección curva granulométrica y

clasificación USCS

Hidrometría

• Definición: Distribución de tamaño partículas menores a 7589.

• NO es necesario para conocer USCS.• Cantidad de suelo: 50 a 100gr• Ensayo: i) conocer %! de la muestra

ensayada, ii) aplicar solución de dispersante y reposo 24hs, iii) agitación mecánica previa, iii) lecturas con hidrómetro 1min, 2min .. 24hr , iv) lavado #200.

• Cuantificación de %; (=>?@AA=) y %C (A@9D)

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23

Equipo de ensayo

Hidrómetro

Hidrometría

• A medida que las partículas sedimentan, el fluido pierde densidad y el hidrómetro cambia su lectura (E)

• E´ = E + ;> ± ;7 − ;H

• I = \´^6

$!→ % pasante

• 6 = I_`

(a!(I)b"J B7→ diámetro

teórico asociado (Stokes)

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24

AOSA - Sedimentometría

Universidad de Buenos Aires - Facultad de Ingeniería

Lab. Materiales & Estructuras - Área Mec. De Suelos

Responsable :

menores a 0,074 mm 95%menores a 0,031 mm 63%menores a 0,017 mm 53%menores a 0,011 mm 39%menores a 0,009 mm 33%menores a 0,006 mm 31%menores a 0,003 mm 27%menores a 0,001 mm 21%FRACCION ARCILLA ( C ) 24%FRACCION LIMO (M) 71%

D = K (L/T) 0.50 P = R´a / W a 1,00 C m 2 Baño térmico 24,2 ºCR´ = R + C t + C m - Cd K 0,013 C t 0,8 C d 7 Tamaño muestra 50,07 gr

TARA P.H. P.S. w Ws#DIV/0! 50,07

TARA P.S.11,25 13,68 gs 2,66 gr/cm3

Peso del suelo a ensayar : 50,07 gr R Lectura del hidrómetro.Estimación de pérdidas: 0,3% W Peso seco del suelo en suspensión.Peso del suelo final: 49,9 gr L Longitud de caída efectiva.

39%

33%

31%

27%

21%

ENSAYO DE SEDIMENTOMETRÍAFecha : 08/04/2019

C. CasagrandeProyecto: 1801

LECTURAS HIDROMETRO DISTRIB. TAMAÑOS

t R R´ L D (mm)

2 min 36 31,8 11,2 0,031

P (%)

63%

53%

30 min 21 16,8 13,7 0,009

15 min 24 19,8 13,2 0,011

0,0175 min 31 26,8 12

0,003Dispersante: Hexametafosf. Sodio 4%Hidrómetro: ASTM 152-H

60 min 20 15,8 13,8 0,006Normativa: ASTM D422-63-R02

250 min 18 13,8 14,2

1440 min 15 10,8 14,7 0,001

AUXILIAR

SUELO HUMEDO

ret. # 2002,43

SUELO SECO

RETENIDO #200

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0,0010,0100,100

% P

asa

Diámetro teórico partícula (mm)

CURVA GRANULOMÉTRICA

arci

lla (>

2um

)

AOSA - Sedimentometría

Universidad de Buenos Aires - Facultad de Ingeniería

Lab. Materiales & Estructuras - Área Mec. De Suelos

Responsable :

menores a 0,074 mm 95%menores a 0,031 mm 63%menores a 0,017 mm 53%menores a 0,011 mm 39%menores a 0,009 mm 33%menores a 0,006 mm 31%menores a 0,003 mm 27%menores a 0,001 mm 21%FRACCION ARCILLA ( C ) 24%FRACCION LIMO (M) 71%

D = K (L/T) 0.50 P = R´a / W a 1,00 C m 2 Baño térmico 24,2 ºCR´ = R + C t + C m - Cd K 0,013 C t 0,8 C d 7 Tamaño muestra 50,07 gr

TARA P.H. P.S. w Ws#DIV/0! 50,07

TARA P.S.11,25 13,68 gs 2,66 gr/cm3

Peso del suelo a ensayar : 50,07 gr R Lectura del hidrómetro.Estimación de pérdidas: 0,3% W Peso seco del suelo en suspensión.Peso del suelo final: 49,9 gr L Longitud de caída efectiva.

39%

33%

31%

27%

21%

ENSAYO DE SEDIMENTOMETRÍAFecha : 08/04/2019

C. CasagrandeProyecto: 1801

LECTURAS HIDROMETRO DISTRIB. TAMAÑOS

t R R´ L D (mm)

2 min 36 31,8 11,2 0,031

P (%)

63%

53%

30 min 21 16,8 13,7 0,009

15 min 24 19,8 13,2 0,011

0,0175 min 31 26,8 12

0,003Dispersante: Hexametafosf. Sodio 4%Hidrómetro: ASTM 152-H

60 min 20 15,8 13,8 0,006Normativa: ASTM D422-63-R02

250 min 18 13,8 14,2

1440 min 15 10,8 14,7 0,001

AUXILIAR

SUELO HUMEDO

ret. # 2002,43

SUELO SECO

RETENIDO #200

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0,0010,0100,100

% P

asa

Diámetro teórico partícula (mm)

CURVA GRANULOMÉTRICA

arci

lla (>

2um

)

#200= 95%C= 24%M= 71%

Planilla delaboratorio

Resultado

Límites de Atterberg

• A. Atterberg (1911) estableció 6 estados de consistencia con propósitos agronómicos.

• A. Casagrande (1932) estandarizó la obtención de 4 estados de consistencia:– KL: límite de contracción (LC)– IL: límite plástico (LP)– LL: límite líquido (LL) – NL: límite de fluidez (LF)

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A. Atterberg

A. Casagrande

c (%)0%

Límite líquido

• Definición: Contenido de agua para el cual la hendidura en el suelo cierra 13 mm al aplicar O = 25 golpes.

• Cantidad de suelo: 50 a 100gr• Ensayo: i) tamizar el suelo por #40, ii)

hidratar con agua destilada y reposar, iii)colocar el suelo en horizontal sobre la copa, iv) marcar la hendidura con ranurador estándar, v) determinar O y tomar muestra para contenido de humedad (4) en zona de hendidura.

• ¿ Y si no me da O = 25 ?

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Límite líquido

• Método 3 puntos: i) se realizan no menos de 3 ensayos y se miden los valores 4 y 15 < O < 35 obtenidos, ii) se construye la curva de fluidez, iii) se determina LL.

• Método de 1 punto: i) se realiza un solo ensayo y se miden los valores 4 y 20 < O < 30 obtenidos, ii) se determina

LL~4 @

fg

J.IfI

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Método 3 puntos

Límite líquido y plástico con método FallCone (BS 1377)

• Cono de 30° con peso 80 y 240gr.• Apoyar el cono, dejar caer por 5 segundos.• LL → cono penetra 20mm en el suelo.• LI → ~LL − 4.2 − ∆4

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2830%

35%

40%

45%

50%

55%

60%

10 100

cont

enid

o de

hum

edad

[%]

penetración del cono [mm]

ExperimentalAjuste LL (pesa 80gr)Ajuste LP (pesa 240gr)

LL=42.5%

Dw

Límite plástico

• Definición: Contenido de agua para el cual se producen agrietamientos al enrollar el suelo en cilindros de 3.2mm

• Cantidad de suelo: aprox. 50gr• Ensayo: i) tamizar el suelo por #40, ii)

hidratar con agua destilada y reposar,iii) fabricar un bollo pequeño de suelo con las manos, iv) rolar el bollo con la palma de la mano hasta ver agrietar los cilindros, v) determinar contenido de humedad (4) con un mínimo 6gr.

• LI = B;4'B;''B;,[

se promedia

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128 Geotechnical Laboratory Measurements for Engineers

The plastic limit is determined by rolling soil on a glass plate to a 3.2 mm (1/8 in.) diameter thread. Historically, rolling has been performed by hand. When the thread crumbles at 3.2 mm, the soil has reached the plastic limit. Refer to Figure 9.13 for an example of how soil threads appear when wetter than the plastic limit, and when at the plastic limit.

After rolling the soil thread to the plastic limit, the soil is placed in a tare for a water content determination and covered immediately to prevent moisture changes. The steps are repeated with another portion of soil, adding the soil to the tare until the mass of soil is at least 6 g. At least three trials are required and the average value is calculated, and reported to the nearest integer as the plastic limit.

A rolling device has been developed to control the diameter of the thread (Bobrowski and Griekspoor, 1992 ) and is included as optional equipment in the current ASTM standard.

Important considerations for the determination of the plastic limit include:

The plate must be made of glass because it is nonabsorbing, providing better moisture control when rolling the soil threads. Maintain even pressure throughout the rolling process. Resist the tendency to increase the pressure as the soil gets drier, as this will cause premature breakage and therefore a higher determination of the water content.

•

•

Plastic Limit by Rolling (ASTM D4318)

0

50

100

150

200

250

0 50 100 150 200 250 300 350 400 450LL (Casagrande)

LL

(Con

e)

Figure 9.12 Comparison between liquid limit determined using Casagrande cup and fall cone. (Adapted from Wasti, 1987)

Figure 9.13 Soil threads rolled to 3.2 mm (1/8 in) without crum-bling (left); soil threads rolled to the plastic limit (i.e., crumbling at 3.2 mm) (right).

Límite líquido y plástico

• Video ensayos: https://www.youtube.com/watch?v=EcXJ961qjGA• SON una propiedad intrínseca del material, no cambian si

no cambia el fluído hidratante del ensayo. • En suelos limosos con predominio de minerales no

plásticos, a veces NO se puede hacer el ensayo de LP o LL y LP. Se informa “sin determinar (SD)”.

• Valores típicos (Zárate-Campana, margen derecha Río Paraná):– Postpampeano (CH): LL = 50 − 80 , LP = 25 − 35– Postpampeano (ML): LL = 25 − 35 , LP = 20 − 25– Pampeano (ML,CL): LL = 30 − 50 , LP = 20 − 35– Puelche (SP, SP-SM): LL = SD, LP = SD

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Límite de contracción

• Definición: Contenido de agua para el cual la muestra sigue perdiendo agua sin reducción de volumen.

• Ensayo: i) se coloca el suelo “bien pasado de agua” en un recipiente de volumen conocido, ii) se seca el suelo al aire, sin que se generen grietas, luego se lo seca al horno, iii) se cubre la muestra de suelo con una capa de cera para que no absorba agua y se lo sumerge para determinar el volumen del suelo seco.

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28 V. PROGRAMA EXPERIMENTAL

1 CARACTERIZACIÓN DEL SUELO

1.1 Selección del material El primer suelo analizado fue extraído de la línea H de subterráneos de la Ciudad de Buenos Aires, esta-ción Corrientes, a una profundidad aproximada de 15 metros . Este suelo es un MH con LL=59 e IP=19 (normas ASTM D-4318-00).

El segundo suelo analizado, fue extraído de una cantera en la zona de T. Suárez. Es un ML con LL=45.5% e IP=9.5 (promedio de seis determina-ciones). En la figura V.1 se muestra la ubicación de los dos suelos en la carta de plastic idad.

MH- OL

ML- OL

0

7

4

4020 60

IP

10

20

CH

CL

CL -ML

50 LL

suelo 2

suelo 1

Figura V.1. Ubicación de los dos suelos ensayados en la carta de plasticidad.

Aunque clasifica como AASHTO A-5, el segundo suelo ensayado (ML) reúne aproximadamente las ca-racterísticas típicas de los materiales utilizados en la construcción de terraplenes, por lo que fue elegido para realizar la batería de ensayos triaxiales.

1.2 Propiedades índice El peso específico de las partículas sólidas es γs = 26.8 kN/m3 (promedio de tres determinaciones , norma ASTM D-0854-02). El Límite de Contracción es 27% (promedio de seis determinaciones, norma ASTM D-0427-04). En la figura V.2 se presenta una fotografía de algunas muestras de los ensayos de contracción en las que se puede apreciar la variación del volumen final, del orden del 1.5% al 2%. En la figura V.3 se presentan los resultados de los ensayos de granulometría e hidrometría.

Figura V.2. Muestras de suelo al finalizar el ensayo de Límite de Contracción.

0.005

10

20

0.05 0.010.1

30

40

50

60

70

80

PT#200[%]

mm

Figura V.3. Curva granulométrica obtenida en el ensayo de hidrometría.

En la figura V.4 se muestra uno de los ensayos de hidrometría.

Figura V.4. Ensayo de hidrometría.

Límite de contracción

• El límite de contracción: L; = 4 − &(&3 ^#5$!

• 4: humedad natural al inicio• ': volumen recipiente• 'H: volumen suelo seco• %h: peso del suelo seco

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Bibliografía

• Normas ASTM – American Society of Testing Materials– D 422 (granulometría, hidrometría)– D 2216 (humedad gravimétrica)– D 2487 (USCS)– D 2488 (inspección tacto-visual)– D 4253 (densidad máxima)– D 4254 (densidad mínima)– D 4318 (Atterberg, LL y LP)– D 4943 (Atterberg, LC)

• Jean-Pierre Bardet – Experimental Soil Mechanics• Germaine – Geotechnical Laboratory Measuerements for Engineers

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